Sleep disorders, including difficulties in either falling asleep or remaining asleep, are increasingly common; one in three adults in the UK are reported to suffer from a sleep disorder of some kind. A lack of sleep can result in impaired concentration and reaction times whilst awake, as well as a general feeling of tiredness. Difficulties in falling asleep can be caused by an inability to ignore conscious thoughts, which may be caused by stress or anxiety.
Severe sleep disorders may be treated using drugs that promote sleep. Although such treatment can be effective for a short time, the drugs typically have undesirable side effects and may be addictive. For this reason many drugs used to improve sleep are approved for short-term use only. Natural herbal therapies for helping a subject to fall asleep are also available. However, whilst these therapies do not usually cause the undesirable side effects associated with other drug based therapies, they are also typically less effective.
Alternative approaches for inducing sleep include meditative approaches in which a stimulus is provided to encourage the subject to relax, for example by providing a light whose intensity varies cyclically so that the subject may match the frequency of their breathing to frequency of the cycles of the light. In this way the frequency of the cycles of the light may be gradually reduced so that the subject is encouraged to slow their breathing at a predetermined rate. An example of such an approach is that implemented by the Nightwave sleep assistant (http://wwww.nightwave.co.uk/index.htm).
Such approaches have the advantage that they have very limited side effects. However, they have the disadvantage that they do not engage with or adapt to the subject, so they may be ineffective for certain individuals or on occasions when the subject finds it particularly difficult to get to sleep.
Another approach to improving sleep involves taking physiological measurements from the subject and attempting to manipulate their surrounding environment to improve sleep. Although such approaches may help the subject to sleep better once they have fallen asleep, they are of limited usefulness in inducing the subject to fall asleep in the first instance.
Embodiments of the present invention aim to provide apparatus and methods for inducing sleep which at least partially mitigate the problems described above.